Generally, a bran processing system for the supercritical carbon dioxide extraction of bran extraction material from bran and fractionation of the bran extraction material. Specifically, a bran processing system for the isolation of a bran extraction material fraction enriched in ferulate-phytosterol esters or oryzanol.
Fractionation of fractured grain such as corn into grain fractions of greater purity including a germ fraction, an endosperm fraction and a bran fraction has several advantages in the context of ethanol production. One advantage of generating grain fractions may be introduction of a greater amount of fermentable biomass into the ethanol production process over conventional methods which introduce whole milled grain. However, in ethanol production systems coupled to grain fractionation systems, the bran fraction may be separated away from the biomass fermented. The bran fraction which may be utilized separately or combined with distillation solids and condensed distillers soluble may be utilized as an animal feed.
A disadvantage of processing the bran fraction for use as animal feed can be that the commercial value of the bran fraction sold as animal feed has less value than the combined commercial value of the bran of the bran fraction utilized as fermentable biomass in the ethanol production process, or as an energy source, and the bran oil of the bran fraction sold directly as bran oil or as fractions of the bran oil for cooking or health supplements.
Additionally, a substantial disadvantage of conventional carbon dioxide extraction of the bran fraction to obtain unrefined bran extraction materials from corn bran or rice bran may not be sufficiently rapid for commercially feasible large scale extraction of the bran extraction material from the amounts of corn bran or rice bran produced by conventional corn and rice milling operations for ethanol production. For example, certain conventional methods of extracting bran extraction material from corn bran utilizes supercritical carbon dioxide at temperatures in the range of 40° C. and 80° C. and pressures between 13.8 and 69 MPa over a period of time of 120 minutes. Taylor, Scott L. and King, Jerry W., “Supercritical Fluid Extraction and Fractionation of Corn Bran Oil”, National Center for Agricultural Utilization Research, Agricultural Research Services, United States Department of Agriculture. For commercial applications it may be more economically feasible when extraction of substantially all of the bran extraction material corn bran or rice bran occurs in a duration of 60 minutes or less.
Another substantial disadvantage of conventional methods of supercritical carbon dioxide extraction of corn bran or rice bran and the method of supercritical fractionation of the resulting corn bran extraction material and rice bran extraction material may be that the methods are conducted separate form one another as individual processes. For example, in a first step corn bran or rice bran can be extracted as above-described and the separated bran extraction material centrifuged to separate oil from waxes and other extract. The resulting oil is then stored until fractionated. One reason for the separate process can be that the fractionation process may not be compatible with the waxes and water resulting from the extraction procedure which may have to be removed from the bran oil prior to fractionation of the oil. Another reason that the extraction process and the fractionation process may remain separate is that conventional methods of supercritical carbon dioxide for fractionation purposes may further include ethanol or other solvents which preclude or make more difficult the recycling of the carbon dioxide from the fractionation process for use in supercritical carbon dioxide extraction of corn bran or rice bran.
The invention addresses each of these problems by providing embodiments of a process for the extraction and fractionation of bran extraction materials.